1. Field of the Invention
The invention relates to a lens barrel structure and an image capture apparatus.
2. Description of the Related Art
In image capture apparatuses, such as digital still cameras and digital video cameras, a lens barrel structure is provided that includes an image capture optical system that contains lenses arranged in a lens barrel and an image device element that captures a subject image.
A lens barrel structure of the type described above has a lens moving mechanism and a lens drive mechanism. The lens moving mechanism holds lenses movably along an optical axis direction, and is supplied with a rotational drive force, thereby to move the lenses along the optical axis direction. The lens drive mechanism supplies the rotational drive force to the lens moving mechanism.
The lens drive mechanism includes, for example, a motor having an output shaft, and a gear train that meshes with a drive gear provided to the output shaft thereby to supply power of the motor to the lens moving mechanism.
In the event of controlling the lens moving mechanism, sensing is performed to sense, for example, the rotation amount and rotation direction of the motor. The sensing is performed by using a sensing plate provided to, for example, an output shaft of the motor or a rotation shaft constituting a gear train, and a detector that detects the rotation of the sensing plate. In this case, when attempting miniaturization, there arises the problem of interference between the sensing plate and the gear train.
As a related art structure including a sensing plate provided to an output shaft of a motor, there has been proposed a configuration that uses a motor of the type having output shafts individually extending from both ends of a housing of the motor. In this case, a drive gear is provided to the one output shaft, and a sensing plate is provided to the other output shaft, thereby to prevent the interference between the support axes of the sensing plate and the gear train (see Japanese Unexamined Patent Application Publication No. 2002-318338, for example).
In addition, as a related art structure, a configuration has been proposed wherein, in view of the fact that gears of a gear train are supported in an inboard (both-side) support manner in many cases, a rotation detection gear dedicated to mesh with a drive gear is newly provided, and a sensing plate rotatable integrally with the rotation detection gear is provided, thereby to prevent interference between the sensing plate and support axes of the gear train (see Japanese Unexamined Patent Application Publication No. 2001-194574, for example).
Nevertheless, however, in any one of the configurations described above, it is disadvantageous to accomplish the miniaturization because the occupation spacing for the sensing plate should be secured. In addition, in the latter configuration, the rotation detection gear to detect the motor rotation needs to be provided, thereby making it disadvantageous to implement, for example, reduction in the number of components and the miniaturization.